Astronomers Discover Millions of New Black Holes and a Rare Type of Galaxy

NASA’s Wide-field Infrared Survey Telescope (WISE) has uncovered millions of supermassive black holes in our universe as well as a strange new type of galaxy, called a hot DOG or dust-obscured galaxy.

“This is a jackpot of black holes, two to three times more than have been found by any other survey,” said astronomer Daniel Stern, during a NASA press conference today.

By carefully scanning the entire night sky in infrared wavelengths, WISE has spotted more than 2.5 million black holes, all of them actively feeding on gas and dust in their host galaxies. Most of these supermassive objects, known as quasars, are roughly 10 billion light-years away.

The most energetic galaxies, the so-called hot DOGs, can pour out more than 100 trillion times the light of our sun. But they are also obscured by a massive halo of dust, which makes them imperceptible in visible wavelengths. WISE’s infrared eyes can peer through the obscuring dust though and determine the hot DOGs’ details. They are exceedingly rare, and WISE has only found about 1,000 of these objects.

The strange hot DOGs may be a key to figuring out galactic evolution in the universe. Despite nearly a century of observations, how galaxies grow and change over time is hot area of research.

Astronomers classify three types of galaxies, two of which are spirals and ellipticals. Spiral galaxies, like our Milky Way, are dominated by a flat disk with stars spinning around the center like planets orbiting a sun. They contain cold gas that can collapse and form young stars. Ellipticals, on the other hand, are full of older stars that swarm around in randomly oriented orbits, like bees buzzing around a hive.

Astronomers think that when two spiral galaxies collide, their dust and stars get scrambled around, suppressing the formation of new stars. Because of the chaotic swirling, this enormous flurry of activity could become hidden behind a layer of gas and dust, forming an object like the hot DOGs that WISE has observed.

“We may be seeing these galaxies at a crucial transformational stage, like watching a butterfly emerging from its cocoon,” said astronomer Rachel Somerville from Rutgers University during the conference.

Images: 1) Each of these orange dots represents a supermassive black hole in the universe. NASA/JPL-Caltech/UCLA. 2) An artist’s rendering of a quasar throwing off enormous amounts of energy while obscured by a massive dust ring. NASA/ESA